Additionally, lamproites may contain leucite, richterite, sanidine, and occasionally nepheline, whereas kimberlites do not. |
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Closer to the contact microcline is replaced by sanidine, and perthitic exsolution in detrital alkali feldspar begins to disappear. |
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The dominant non-clay mineral composition of the coarse fraction consists of biotite, quartz, and sanidine with lesser amounts of apatite and zircon. |
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Trachyte tuffs contain little or no quartz but much sanidine or anorthoclase and sometimes oligoclase feldspar, with occasional biotite, augite and hornblende. |
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